The Effect of ZnO Nanorods Morphology on Electrical Properties of Perovskite Solar Cells

Perovskite solar cells have attracted the researchers' attention because they are one of the most promising candidates that are cheap, easy to fabricate and high-efficiency solar cell. ZnO nanorods (ZnO NRs) can be used as an electron and hole recombination barrier to improve the perovskite solar cell performance. This research aimed to investigate the effect of growing time on the characteristics of ZnO NRs and its application for perovskite solar cell device. The ZnO NRs was synthesized on ITO substrate by hydrothermal method at the different growing times of 4, 6, and 8 hours. The CH₃NH₃PbI₃ perovskite solar cells were deposited on the top of ZnO NRs/ITO thin films by a two-stage spin coating method. The solar cell devices were characterized by using XRD, SEM-EDX, FTIR, UV-vis, and LCR meter. The results showed that ZnO NRs/ITO thin films were formed homogeneously and vertically oriented on all ITO substrates with hexagonal structures of zincite phases. When the growing time of ZnO NRs increased, the degree of homogeneity, density, and length of the rods enhanced as well. All the samples have the bandgap around 3.05 eV. The FTIR results showed the absorbent functional forces at 870 cm⁻¹ and 1250 cm⁻¹ related with H-C-N wavelengths, and ZnO wavelength ranges from 400 to 515 cm⁻¹. The CH₃NH₃PbI₃ perovskite solar cell device still contained PbI₂ as impurities phase. The longer the growing time, the rods resulted by ZnO NRs had the wider diameter and the longer length and they were more homogenous. Meanwhile, the effect of the number of PbI₂ impurities resulted in the higher dielectric and smaller current. (paper)